Question

When a sample of a gas is kept at constant pressure the volume and Kelvin temperature of the gas are?

Answer 1

They are directly proportional...

Explanation:

If the sample of gas has a constant number of moles and kept at a constant pressure, we get a case of one of the gas laws, in this case it's Charles' Law.

Charles' Law states that,

When the pressure on a sample of a dry gas is held constant, the Kelvin temperature and the volume will be directly related.

Taken from here.

In an equation form, it means that `VpropT` or `V_1/T_1=V_2/T_2`.

So, if the temperature in Kelvin increases, then the volume will also increase, and if the temperature decreases, then the volume decreases.